Testing apparatus



Inventors Attnrne F. MITCHELL ET AL TESTING APPARATUS Filed May 21, 1954 Franklin Mit chell rlnhn G- Enmtcm Ehy arch 10, 1936.

Patented Mar. 10, 1936 UNITED STATES PATE TESTING APPARATUS Application May 21, 1934, Serial No. 726,798

4 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates generally to testing apparatus and more particularly it has reference to means for submitting an open-ended container such as a projectile to an internal pressure for the purpose of detecting leaks and defects in the container.

The purpose of this invention is to provide a testing apparatus which permits rapid application andremoval of the container and which may be operated without loss of the pressure medium in the container.

With these and other objects in view the testing apparatus includes a novel plunger having a movable piston, a rigidly supported sleeve slidably embracing the piston, and a resilient packing interposed between the piston and the sleeve.

A preferred embodiment of the invention is illustrated in the accompanying drawing, in which Fig. 1 is a longitudinal sectional view of the improved apparatus showing the arrangement of the parts prior to application or after removal of the container.

Fig. 2 is a similar view showing the arrangement of the parts during testing of the container.

Referring to the drawing by characters of reference there are shown elements of a conventional press having a fixed head 5 and a platen 6 arranged for movement towards and away from the fixed head. A bracket 7 secured to the fixed head by bolts 8-8 is formed with an aperture 9 leading into a recess in the upper part of the bracket. The recess is in alignment with an aperture H in the fixed head 5.

A plunger carried by the fixed head comprises a piston having a piston head 12 at its lower end and a piston rod 13 whose upper end is slidably inserted through the aperture 9 in the bracket. The upper end of the piston rod is provided with threads for receiving one or more nuts I 4 which seat on the floor of the recess l0 and support the piston as well as limiting its downward movement.

A sleeve l slidably mounted on the piston rod is maintained against the bracket 1 and in spaced relation with respect to the piston head by a packing interposed between the lower face of the sleeve and the upper face of the piston head. The packing consists of a series of rings mounted on the piston rod, the end rings l6 and I1 preferably being of metal and confining a resilient rubber ring I8 and a fiber ring l9 or equivalent packing and sealing members.

In operation, the container 20 that is to be tested, is provided with a predetermined quantity of a fluid 2|, such as water, and placed on the platen 5 of the press with its mouth in line with the plunger. The press is now operated to raise the platen and cause the plunger to enter the mouth of the container and act against the fluid 2|. As pressure is exerted, the piston yields and in moving upwardly the piston head l2 compresses the packing against the non-yielding sleeve l5 and causes the packing to expand laterally into sealing relation with the inside wall of the container, and prevents escape of the fluid.

The pressure developed within the container may be sufiiciently high to stress the container to the limit of the particular metal of which it is composed. With projectiles the pressure developed is about 30,000 pounds per square inch. If the container has leaks or defects the fluid will escape through the walls and afford evidence of such a condition. The packing forms a perfect seal to prevent escape of the fluid past the plunger since the movable piston is subject to the pressure within the container and transmits this pressure to the packing.

When the test is completed the platen is lowered and the container is removed from the plunger by any suitable stripping device; operated manually or mechanically. In order to facilitate removal of the container the upper end of the piston rod may be struck a sharp blow. This will relieve the pressure exerted against the packing and at the same time the piston will act through the fluid and tend to remove the container.

After each test a heavy grease coating is applied to the packing. Adjustment of the packing is obtained by acting on the nuts M.

We claim:

1. In testing apparatus, a press comprising a movable platen, a fixed head spaced from the platen and having an aperture, a bracket secured to the head and having a recess in its upper portion in communication with the aperture in the head, said bracket also having an aperture leading to its recess, a piston rod passing through the aperture in the bracket, a nut on the piston rod seated on the floor of the recess in the bracket, a piston head on the lower end of the rod, a sleeve on the piston rod and bearing against the bracket, and compressible packing between the piston head and sleeve.

2. In testing apparatus, a fixed head, a piston rod slidably carried by the head, a member on one end of the piston rod and seating on the fixed head, a piston head on the other end of the piston rod, a sleeve on the piston rod and bearing against the fixed head, compressible packing between, the piston head and the sleeve, a support fora recessed test specimen, and means for axially moving said support relative to the fixed head for causing the piston to enter the specimen.

3. In testing apparatus, a fixed head; 'apiston carried by the head and movable relative thereto, a head on the piston, a sleeve on the piston and bearing on the fixed head, compressible packing between the piston head and the sleeve, a. support for a recessed test specimen, and means for axially moving said support relative to the fixed head for causing the piston to enter the specimen.

4. In testing apparatus a fixed head, a piston movable relative to the head, compressible packing' between the movable piston and the head, a support for a recessed test specimen, and means for axially moving said support relative to the head. for causing the piston to enter the specimen.

FRANKLIN MITCHELL. JOHN G. BOOTON. 

